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<B><A HREF="ERF.html">ERF(3)</A></B>		       FreeBSD Library Functions Manual 		<B><A HREF="ERF.html">ERF(3)</A></B>


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<H2>NAME</H2><PRE>
     <B>erf</B>, <B>erff</B>, <B>erfc</B>, <B>erfcf</B> - error function operators


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<H2>SYNOPSIS</H2><PRE>
     <B>#include</B> <B>&lt;math.h&gt;</B>

     <I>double</I>
     <B>erf</B>(<I>double</I> <I>x</I>)

     <I>float</I>
     <B>erff</B>(<I>float</I> <I>x</I>)

     <I>double</I>
     <B>erfc</B>(<I>double</I> <I>x</I>)

     <I>float</I>
     <B>erfcf</B>(<I>float</I> <I>x</I>)


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<H2>DESCRIPTION</H2><PRE>
     These functions calculate the error function of <I>x</I>.

     The <B>erf</B>() and the <B>erff</B>() functions calculate the error function of x;
     where

	   erf(x) = 2/sqrt(pi)*integral from 0 to x of exp(-t*t) dt.

     The <B>erfc</B>() and the <B>erfcf</B>() functions calculate the complementary error
     function of <I>x</I>; that is <B>erfc</B>() subtracts the result of the error function
     <B>erf</B>(<I>x</I>) from 1.0.  This is useful, since for large <I>x</I> places disappear.


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<H2>SEE ALSO</H2><PRE>
     <B><A HREF="math.html">math(3)</A></B>


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<H2>HISTORY</H2><PRE>
     The <B>erf</B>() and <B>erfc</B>() functions appeared in 4.3BSD.

4.3 Berkeley Distribution	April 20, 1991				     1
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